A few years ago, as I recall, there was a push for drivers to put on headlights during the daytime and for a few years, many cars had a setting "DRL" for low level headlights. Evidently, subsequent research seems to have indicated that this is not at all effective, in most cases for passenger cars, at increasing safety.

A used car we just purchased has the DRL setting. I turn on headlights (or use the DRL) when very overcast or rainy or as dark is near, but am undecided about regular daytime.

A couple of our older cars allow you to modify whether you want DRL's on or not. I disable them as I prefer to be in charge of when my headlamps are on. I also use higher-end bulbs that have a much shorter lifespan than the long-life bulbs everyone has moved to since the advent of DRL's and I dislike having to replace them a couple times per year.

My car has DRL always on - cannot turn them off. If there is any question on visibility I turn on the headlights since this also turns on the taillights. I believe full headlights are required when it rains in my state.

edit: found this on the state website

Maryland law now requires headlights to be used whenever windshield wipers are used continuously because of visibility conditions.

When you discover that you are riding a dead horse, the best strategy is to dismount.

My car, a Subaru Impreza hatchback, has automatic low level headlights when you start the car up. They are not enough for me, I have seen too many idiots make dangerous moves on the road too often, like blatantly ignoring stop signs. I put on the regular headlights in the daytime, understanding that my choice will reduce their lifetime. They seem to make most people pay more attention to their surroundings when they are driving.

My car has DRL always on - cannot turn them off. If there is any question on visibility I turn on the headlights since this also turns on the taillights. I believe full headlights are required when it rains in my state.

edit: found this on the state website

Maryland law now requires headlights to be used whenever windshield wipers are used continuously because of visibility conditions.

True in Massachusetts too, and they explicitly state that running lights are not enough.

A few years ago, as I recall, there was a push for drivers to put on headlights during the daytime and for a few years, many cars had a setting "DRL" for low level headlights. Evidently, subsequent research seems to have indicated that this is not at all effective, in most cases for passenger cars, at increasing safety.

A used car we just purchased has the DRL setting. I turn on headlights (or use the DRL) when very overcast or rainy or as dark is near, but am undecided about regular daytime.

Opinions?

My car has DRL by default—no way to turn off. I use common sense for headlights. Wipers on is one criteria but basically, any conditions which necessitate better “be seen” gets them turned on. I suspect that the reason that DRL did not improve safety is that any behavior adopted by the multitudes which was once rare, the human brain has a way of discounting, neglecting or otherwise turning off. Going from no cars with lights on a sunny day to a sea of cars with DRL is exactly what I’m talking about here.

Headlights on always. Not automatic lights, not daytime running lights.

I have seen lots of cars at dusk with the daytime running lights on, but the taillights are NOT on. That's the problem with automatic lights. I want my taillights on all the time.

One of my few beefs with Tesla: you can’t specify headlights and taillights on all the time, as you can with Volvo. I always turn them on, but then forget to turn them off when leaving the vehicle, until the beeping reminds me.

I was driving in the direction of the setting sun yesterday, and it amazed me how many people don’t have the imagination to realize how helpful taillights are in that situation.

Evidently, subsequent research seems to have indicated that this is not at all effective, in most cases for passenger cars, at increasing safety.

I couldn't find the 'subsequent research' that you are citing though I saw that a 2004 NHTSA study was more positive than a subsequent one in 2008. A more recent study done in Minnesota with what seems like better methodology shows more of an effect than the 2004 NHTSA study. The Minnesota study showed an increased risk of crashes of about 1.75 for cars without DRL with other cars, bicycles and pedestrians and an increased risk of fatal crashes of 1.5 in vehicular crashes. My understanding is that there has been no study that has shown an increased risk of having DRL and most done in various countries show a decreased crash risk. Certainly in northern latitudes and bad weather, it is hard to imagine that there wouldn't be some benefit.

Headlights are automatically on in the daytime by law in Canada and cannot be disabled. My understanding is that most vehicles are wired such that the high beam bulb is used at a lower setting than in night time use. I agree with others that many times I am more interested in having my tail lights on when driving near dusk or dawn or in inclement weather and turn these on if the automatic low light sensor hasn't already done so.

'It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so!' Mark Twain

My car doesn't have automatic headlights and it's annoying to sometimes find I've been driving for miles at night with no lights on at all. If I had both settings I would use both settings - make everything automatic.

All of our cars have an "auto" setting which turns the DRLs on unless it is dark enough to turn the headlights on. I use that setting but will over-ride it when the car proves itself to be dumber than I am, as it does occasionally.

I wish other cars had this setting, too. There might be studies showing that they're ineffective, but living in the outer boroughs of NYC, it's a huge help when other cars are running with DRL/headlights on smaller streets- you can see the reflection off of parked cars when you approach an intersection. I find it's actually easier to go through intersections at night than during the day because of this.

My DRLs are always on (when headlights are off).
I manually turn on the headlights anytime driving conditions are less than ideal which encompasses many possible situations including lighting, precipitation, traffic, etc.

My car has DRL always on - cannot turn them off. If there is any question on visibility I turn on the headlights since this also turns on the taillights. I believe full headlights are required when it rains in my state.

edit: found this on the state website

Maryland law now requires headlights to be used whenever windshield wipers are used continuously because of visibility conditions.

True in Massachusetts too, and they explicitly state that running lights are not enough.

When I drive with headlights, I turn on the fog lights as well. They don't do a lot for me being able to see, but I believe they make my car more visible than without them.

I notice a lot of people around here drive with their fog lights on when there is no fog. I always wonder if this is intentional or accidental.

I see people driving with their flashers (in addition to headlights) on in heavy rain or fog. I don't like it much in the fog, but I hate it in the rain.

I have mixed feelings about this. Recently I was driving in white out conditions, and I was having trouble seeing the car in front of me, even though its lights were on. I turned on my flashers. I know the annoyance factor. It is a fine line between being visible and just being annoying.

When I drive with headlights, I turn on the fog lights as well. They don't do a lot for me being able to see, but I believe they make my car more visible than without them.

I notice a lot of people around here drive with their fog lights on when there is no fog. I always wonder if this is intentional or accidental.

I see people driving with their flashers (in addition to headlights) on in heavy rain or fog. I don't like it much in the fog, but I hate it in the rain.

I have mixed feelings about this. Recently I was driving in white out conditions, and I was having trouble seeing the car in front of me, even though its lights were on. I turned on my flashers. I know the annoyance factor. It is a fine line between being visible and just being annoying.

Yep. I completely understand. It is a genuine conflict. The driver wants to be seen, but the flashers impair the vision of other drivers--particularly the one directly behind.

edit: Just realized that isn't the point you made. I have not experienced the flashers improving my vision, so I really can't comment on that aspect.

When I drive with headlights, I turn on the fog lights as well. They don't do a lot for me being able to see, but I believe they make my car more visible than without them.

I notice a lot of people around here drive with their fog lights on when there is no fog. I always wonder if this is intentional or accidental.

I see people driving with their flashers (in addition to headlights) on in heavy rain or fog. I don't like it much in the fog, but I hate it in the rain.

I have mixed feelings about this. Recently I was driving in white out conditions, and I was having trouble seeing the car in front of me, even though its lights were on. I turned on my flashers. I know the annoyance factor. It is a fine line between being visible and just being annoying.

Yep. I completely understand. It is a genuine conflict. The driver wants to be seen, but the flashers impair the vision of other drivers--particularly the one directly behind.

edit: Just realized that isn't the point you made. I have not experienced the flashers improving my vision, so I really can't comment on that aspect.

No, not claiming flashers will improve your vision. They can make your car more visible to the car behind you when you are in very low visibility conditions, like a snow white out or heavy fog. On the other hand, I get annoyed when you are following a car with their flashers on when it really is not necessary; it is a distraction.

Also, I believe that you are supposed to use flashers on an interstate highway when you are below 40 mph.

When I drive with headlights, I turn on the fog lights as well. They don't do a lot for me being able to see, but I believe they make my car more visible than without them.

If you have real fog lights you should not do this. Properly designed fog lights will dazzle oncoming and following drivers. Much worse than high beams. If they don't dazzle they are marginal or useless as fog lights.

My vehicle has sensors for that. If the car is running the running lights are on, if it dark enough out due to weather or evening it turns the headlights on. If it starts to rain it turns the wipers on..... the more rain the faster they go. Car handles all of that and it is a 2013.

When I drive with headlights, I turn on the fog lights as well. They don't do a lot for me being able to see, but I believe they make my car more visible than without them.

If you have real fog lights you should not do this. Properly designed fog lights will dazzle oncoming and following drivers. Much worse than high beams. If they don't dazzle they are marginal or useless as fog lights.

A lot of cars have fog lights these days, and I don't find the dazzling to be true. I wonder if you are confusing fog lights with "driving lights," which look kind of similar to fog lights but are aimed at long range, beyond range of standard headlights.

Fog lights point down to illuminate the area directly in front of the car. The idea is if there is fog, the area directly in front of the car is better illuminated. Sometimes, in very heavy fog, the headlights are reflected back at you from the fog; in these cases, it may be better to turn off the headlights and use only the fog lights (be sure to keep your parking lights on so there is visibility from behind).

As a sidenote, I'm honestly surprised that so many bogleheads are driving new model cars or high-end cars with all these features!

My 2005 Mazda has none of them as it's too old...and my 2012 has only base features so I drive both with headlights on at all times. One being silver and the other charcoal makes them both blend too much into the road and I hate people turning left in front of me when I don't have lights on.

We've always done full headlights all the time. I changed a lot of bulbs and always bought on line and kept a stash in the garage. Most of our vehicles now have the "auto" setting with daytime running lights (lower brightness) and are HID or LED. I've been on the fence about this. I guess I'll go back to full-on headlights. HIDs last a long time but replacement is $$$. LEDs "should" last (almost) forever, but that has not been my experience with household LED bulbs.

Can't say this enough times: once you drive a car with HID or LED (vs. conventional "halogen"), you will never go back. One of the most important options you can get, imo. And autodimming of high-beams is nice but it's too sensitive to ambient light and too slow to turn the brights back on, imo.

As a sidenote, I'm honestly surprised that so many bogleheads are driving new model cars or high-end cars with all these features!

My 2005 Mazda has none of them as it's too old...and my 2012 has only base features so I drive both with headlights on at all times. One being silver and the other charcoal makes them both blend too much into the road and I hate people turning left in front of me when I don't have lights on.

My 2000 S-10 has auto lights. No power anything (including engine...2.2 liter), but has headlights on all the time. I will be checking the taillights though. I think they are also on, but want to be sure. I recall verifying once.

My car has DRL always on - cannot turn them off. If there is any question on visibility I turn on the headlights since this also turns on the taillights. I believe full headlights are required when it rains in my state.

edit: found this on the state website

Maryland law now requires headlights to be used whenever windshield wipers are used continuously because of visibility conditions.

True in Massachusetts too, and they explicitly state that running lights are not enough.

Same in PA, although a lot of people do not seem to know about it.

Wouldn't that just encourage drivers to keep their wipers off too when they would otherwise be needed?

I wish other cars had this setting, too. There might be studies showing that they're ineffective, but living in the outer boroughs of NYC, it's a huge help when other cars are running with DRL/headlights on smaller streets- you can see the reflection off of parked cars when you approach an intersection. I find it's actually easier to go through intersections at night than during the day because of this.

Studies show that DRLs are effective, but only statistically significant for vans and light trucks in the USA. The are more effective for northern countries:

GM lobbied to get them mandated in the US, but the NHTSA never mandated them. They make motorcycles less conspicuous. Motorcyclist lobby against DRLs.

Lots of cars have DRLs as standard equipment, but they are disabled. Disabled by the owner or perhaps left disabled by the dealer, not sure. As of 1999: "They're standard on all 1999 GM, Lexus, Saab, Suzuki, Volkswagen, and Volvo models, as well as the Toyota Avalon, Camry Solara, Corolla, and Sienna. They are optional on the Toyota Camry and Tacoma and on some BMWs. GM offers retrofit DRL kits for vehicles that don't already have DRLs. The kits can be used on non-GM models, as well." (http://www.usroads.com/journals/rmej/9912/rm991203.htm). If you just notice the cars that don't have them as you drive around, you will notice that they are disabled on many vehicles (GM vehicles, for instance) that have them as standard equipement. I once had then enabled by a dealer on a VW that I bought for my daughter.

Last edited by tadamsmar on Mon Jan 01, 2018 5:03 pm, edited 4 times in total.

When I drive with headlights, I turn on the fog lights as well. They don't do a lot for me being able to see, but I believe they make my car more visible than without them.

If you have real fog lights you should not do this. Properly designed fog lights will dazzle oncoming and following drivers. Much worse than high beams. If they don't dazzle they are marginal or useless as fog lights.

A lot of cars have fog lights these days, and I don't find the dazzling to be true. I wonder if you are confusing fog lights with "driving lights," which look kind of similar to fog lights but are aimed at long range, beyond range of standard headlights.

Fog lights point down to illuminate the area directly in front of the car. The idea is if there is fog, the area directly in front of the car is better illuminated. Sometimes, in very heavy fog, the headlights are reflected back at you from the fog; in these cases, it may be better to turn off the headlights and use only the fog lights (be sure to keep your parking lights on so there is visibility from behind).

Many cars these days come with fog lights. Unfortunately, lots of people drive with their fog lights on and they do create problems for a lot of drivers -including me. The effect is almost as bad as someone who does not turn off their bright lights (some halogen headlights are almost as bad). These are the cars with lights down below normal headlights.

I don't know if the drivers who do this simply don't know that the fog lights are on (never read their manual), or who don't know the difference between headlights and fog lights, or who don't realize (or care) that they're blinding oncoming vehicles. I think some people like the higher illumination that fog lights provide, but don't realize (or care) that they're almost as bad as having your brights on.

There's a reason the things are called "fog lights". I have long thought that there needs to be a public information drive to raise awareness that unless you're driving in fog, your fog lights need to be OFF.

Headlights & bright lights quite often are not angled properly - there are guidelines for this, but even in new cars, they're often not correct. I would suspect it is equally as true of fog lights. Of course, most people aren't going to pay a mechanic $100 to adjust.

I agree with livesoft that having tail lights on is at least as important as having DRL on, especially in the rain, overcast weather, or dawn/dusk.

Unfortunately, lots of people drive with their fog lights on and they do create problems for a lot of drivers -including me.

I drive all the time at night with my fog lights on to help illuminate the eyes of deer in the ditches. Living in the state with the highest rate of deer/vehicle collisions, it has save my bacon more than once to be able to see a deer heading up the ditch to cross the road in front of me. At night when just the fog lights are on and nothing else, they illuminate about 40 feet in front of the vehicle and about ten to fifteen feet on each side. Way less than the average low beams. The eyes of the deer will reflect with the fog lights about 40 feet to the side and while using low beams alone, I'm lucky to see anything of a deer until it is less than 10 feet from the road.

Unfortunately, lots of people drive with their fog lights on and they do create problems for a lot of drivers -including me.

I drive all the time at night with my fog lights on to help illuminate the eyes of deer in the ditches. Living in the state with the highest rate of deer/vehicle collisions, it has save my bacon more than once to be able to see a deer heading up the ditch to cross the road in front of me. At night when just the fog lights are on and nothing else, they illuminate about 40 feet in front of the vehicle and about ten to fifteen feet on each side. Way less than the average low beams. The eyes of the deer will reflect with the fog lights about 40 feet to the side and while using low beams alone, I'm lucky to see anything of a deer until it is less than 10 feet from the road.

That makes sense. Just turn them off when there is oncoming traffic, just the way you would your brights. Fog lights combined with headlights is blinding for many.
I live in a city where people don't have that excuse. At least you're aware they're on, and that they are fog lights - more than I can say for most people I see using them (who don't turn them off when there's oncoming traffic).

A lot of things sold as "fog lights" and "driving lights" are just fashion statements.

A true front fog light is mounted as low as possible (The greater the distance between the drivers eye and the light the better, because this reduces back scatter). This means that the upper cut off has to be above the horizontal, at least if there is the slightest dip or bump in the road, so you are going to intermittently shine a bright light directly into the eyes of oncoming drivers. A front fog light should also be matched with a rear fog light, which is a tail light of unusual brightness, and also has dazzle potential.

Most state drivers manuals say to turn the darn things off if there is no fog. NY drivers manual says "When visibility improves, you can switch off your fog lights to reduce the glare that can bother other drivers." In places such as the UK where there is a lot of fog and the design of fog lamps is taken seriously and say "must switch off if there is no fog".

I suppose there is little downside to turning on headlights all the time -

There is actually. Unfortunately I can not provide a link to the study, but about 10 years ago it was found that if cars have the DLR on all the time, motorcycles are at HIGHER risk to be hit (again) since it was first for motorcycles to have their lights on in daytime in order to improve visibility of their approach.

Since I get a premium reduction from my insurance for having DLR in my vehicles, I can only assume that their statistic clearly shows a benefit - otherwise they would not shell out the money me thinks...that's all the proof I need.

Everything you read in this post is my personal opinion. If you disagree with this disclaimer, please un-read the text immidiatly and destroy any copy or remembrance of it.